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FirefoxWeb browser · Mozilla

CVE-2016-5281

CRITICAL · 9.8 CVSS v3.0 Published 2016-09-22
Fix available
A fix is available. Upgrade to after 48.0.2 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Use-after-free vulnerability in the DOMSVGLength class in Mozilla Firefox before 49.0, Firefox ESR 45.x before 45.4, and Thunderbird < 45.4 allows remote attackers to execute arbitrary code by leveraging improper interaction between JavaScript code and an SVG document.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A use-after-free vulnerability in the DOMSVGLength class in Mozilla Firefox and Thunderbird allows remote attackers to execute arbitrary code through improper interaction between JavaScript and SVG documents.

MitigationApply vendor patches by updating Firefox to 49.0 or later, Firefox ESR to 45.4 or later, or Thunderbird to 45.4 or later.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FirefoxWeb browser
Affected:<= 48.0.2= 45.0= 45.0.1= 45.0.2= 45.1.1= 45.2.0= 45.3.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Firefox version
    In Firefox, go to Help > About Firefox. From command line, run: firefox --version
    Affected if Version is 48.0.2 or lower, or exactly 45.0, 45.0.1, 45.0.2, 45.1.1, 45.2.0, or 45.3.0
  2. Identify installed Thunderbird version
    In Thunderbird, go to Help > About Thunderbird. From command line, run: thunderbird --version
    Affected if Version matches the Firefox 45.x or 48.x vulnerable ranges, since Thunderbird shares the same rendering engine
  3. Confirm SVG processing is occurring
    Review whether the browser or mail client is processing or rendering SVG documents or content, particularly those that may contain embedded JavaScript
    Affected if SVG documents with JavaScript are being processed - this is the specific interaction that triggers the use-after-free in DOMSVGLength class

A system is affected if it runs an affected Firefox or Thunderbird version (48.0.2 or lower, or exactly any of 45.0 through 45.3.0) and processes SVG content with embedded JavaScript.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 48.0.2
Interim mitigation

Apply vendor patches by updating Firefox to 49.0 or later, Firefox ESR to 45.4 or later, or Thunderbird to 45.4 or later.

Recommended fix High confidence

Firefox 49.0 or later (or Firefox ESR 45.4 or later for ESR releases)

  1. Verify current Firefox version by navigating to Help > About Firefox
  2. If running Firefox <= 48.0.2 or 45.x series <= 45.0.2, download Firefox 49.0 or later from the official Mozilla website (www.mozilla.org)
  3. If running Firefox ESR 45.x, download Firefox ESR 45.4 or later
  4. Close all Firefox instances completely
  5. Install the updated version, allowing it to overwrite the existing installation
  6. Restart Firefox and verify the new version in Help > About Firefox
Caveat Minor: Some legacy add-ons incompatible with Firefox 49+ may need updates or replacement

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Firefox Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2016-5281 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data